Sacrificing Surfactants to Improve Oil Recovery: A Fluid Density Functional Theory Study

In the chemically enhanced oil recovery (CEOR) processes, heavy components in crude oil, such as asphaltenes, adhere to reservoir rocks, significantly impeding crude oil extraction. Surfactants are frequently utilized to improve oil recovery due to their ability to reduce interfacial tension (IFT) and modify surface wettability. Nevertheless, indiscriminate surfactant usage may result in resource wastage and hinder the attainment of optimal recovery outcomes. Therefore, it is urgent to accurately and efficiently screen out optimal surfactants suitable for different oil fields. This work employs fluid density functional theory (FDFT) to investigate the competitive adsorption mechanism of surfactants and asphaltenes on rock interfaces. We examined the impact of surfactants on asphaltene adsorption and determined the optimal surfactant concentration and chain length for differing reservoir electrical properties and asphaltene compositions. Furthermore, a comprehensive assessment of surfactants was conducted, considering both performance and economic factors. The findings contribute to a deeper comprehension of the displacement effect of surfactants on asphaltenes and offer scientific screening solutions for surfactants in oil recovery processes.